火灾下隧道衬砌混凝土细观损伤演化

为了客观地反映火灾下衬砌混凝土高温损伤的本质，需要考虑混凝土结构特性的不均匀性.结合细观损伤力学，建立混凝土热力耦合作用下衬砌混凝土细观损伤过程的数值模型，该模型考虑了隧道衬砌结构顶部的受力状态，可以研究隧道衬砌混凝土在火灾过程中的力学行为与损伤过程.研究结果表明，火灾对隧道衬砌混凝土的力学性质和损伤演化过程影响显著，界面的力学特性决定宏观强度的差异；基于强度等效理论，隧道衬砌混凝土在RABT火灾荷载下的累积等效烧损深度呈曲线变化；细观数值模拟下损伤单元比例与等效烧损深度存在较好的线性关系.

Meso damage evolution of tunnel lining concrete under fire

The heterogeneity of concrete structure needs to be considered for the study of concrete damage, in order to objectively reflect the essence of the high temperature damage of concrete. A numerical model was established to analyze the meso-damage process of concrete under thermal mechanical coupling combined with meso-damage mechanics.The model considered the stress state at the top of the tunnel lining. The mechanical behavior and damage process of tunnel lining concrete in the course of fire were analyzed.Results show that the influence of fire on the mechanical properties and damage evolution process of tunnel lining concrete is significant, and the mechanical properties of the interface determine the differences in macroscopic strength. The cumulative equivalent burning loss depth of tunnel lining concrete under the RABT fire loading shows curve variation based on the strength equivalence theory. In the meso-scale numerical simulation, there is a good linear relationship between the damage unit ratio and the equivalent burning loss depth.